SunriseBrowser isn't really meant for every day use. Think of it more as a development tool. It uses Safari's engine to render the pages (you can even access Safari's bookmarks from within SunriseBrowser), but unlike Safari, it can tell you a whole lot more about the mechanics of the page you're viewing.

If you wish, you can view the source code of the page in a semi-transparent overlay window (see below), as well as the linked CSS files where applicable.

You can also instantly validate the page, copy the title of the page, switch between various fixed window sizes... You can even (this is the best feature of all) save the page as a single continuous PDF.